A tubing locking mandrel is used for attaching wellbore tools such as a flow control device to the interior of wellbore tubing and is deployed in the wellbore by a running tool inserted into the wellbore tubing, by wireline, slickline, coiled tubing, or the like. The current locking mandrels will have an outer profile configured to engage with a corresponding interior recess or locking profile of a downhole landing “nipple” incorporated into the wellbore tubing. An example of such a locking: mandrel is an OTIS® X® lock which designed to mate with the locking profile of an OTIS® XN® landing nipple. These locking mandrels have locating dogs and spring loaded lock keys that are used to locate the corresponding locking profile and lock the locking mandrel in place onto the landing nipple. Such locking mandrels are considered “selective” locking mandrels because when inserted into the wellbore tubing, the locking mandrels can be moved downhole through multiple landing nipples along the wellbore tubing to a depth or wellbore position where a desired landing nipple is located.
Tubing locking, mandrels are locked or set into a landing nipple by attaching the locking mandrel to a running tool and inserting the running tool and attached locking mandrel into the wellbore tubing and then moving the running tool and locking mandrel to a position beyond the desired landing nipple. The running tool and locking mandrel are then pulled upward in the wellbore tubing until the locating dogs on the running tool engage with or catch the corresponding locking profile in the desired landing nipple. The locking mandrel is then pulled further upward with sufficient force to shift the locking mandrel into a “controlled position” to where it is then pulled further upward to a position above the desired landing nipple. After being so positioned, the locking mandrel and running tool is then lowered until the spring loaded lock keys of the locking mandrel sit upon a matching shoulder in the desired landing nipple preventing further downward movement of the locking mandrel. A downward force is then applied on the locking mandrel, through jarring or by the sit down weight of the coiled tubing and attached tools, to shear a pin in the running tool and shift a sleeve on the locking mandrel, sometimes called an “expander mandrel”, to a position behind the lock keys to prevent the spring loaded lock keys from collapsing back into the body of the locking mandrel. An upward force is then applied on the running tool and attached locking mandrel to shear a core retainer pin holding the locking mandrel to the running tool. When the core retainer pin holding the running tool to the locking mandrel is sheared, the running tool may then be pulled out of the wellbore tubing leaving the locking mandrel set in place on the landing nipple.
Current tubing locking mandrels have a number of design deficiencies which often prevent these locking mandrels from being properly set into a landing nipple without costly and time consuming problems. Current tubing locking mandrels typically have a lock body with an enlarged outer diameter or O.D. and thermoplastic seals called Vee packing stacks. The lock body and Vee packing stacks must be moved past restricted or constricted sections in the wellbore tubing such as tubing connections (especially over-torqued tubing connections), landing nipple profiles, and other restrictions in the wellbore tubing, such as paraffin wax or a build-up of scale, hydrate, asphaltene or corrosion. The only way to move the locking mandrels beyond the wellbore the restrictions is to use a jarring tool to apply an impact load or jar down on the running tool and subsequently the locking; mandrel.
When jarring on current running tools and locking mandrels in order to move beyond a tubing restriction, such jarring often results in prematurely shearing the top “setting” shear pin of these running tools. Often when jarring a running tool and locking mandrel past a wellbore restriction, the jar, the running tool and the attached locking mandrel will fall through the restriction to a position where they are abruptly stopped. This abrupt stopping will often cause a lower retainer pin in the running tool to shear. The shearing of any attachment pin in a running tool or locking mandrel can and usually does prevent the locking mandrel from setting properly into a landing nipple. These problems frequently occur when running tools ale worn, damaged, or have not been properly maintained.
A wellbore may be drilled as a “horizontal” well that deviates substantially from vertical. Attempting to jar down on current running tools to set a locking mandrel in a deviated wellbore can be problematic because the wellbore geometry makes it difficult to apply the jarring force needed to shear the setting pins and set the locking mandrel. The difficulty associated with applying these downward jarring forces in “horizontal” wellbores increases the time associated with setting the locking mandrel and increase the risk that the locking mandrel will be not be properly set in the landing nipple and that it will be set in an undesirable location. Similar problems occur when current locking mandrels are being run into a wellbore that has heavy or viscous wellbore fluids. Heavy or viscous wellbore fluids will often impede the jarring forces required to shear, the setting pins in current running tools.
Paraffin buildup in a wellbore that has not or cannot be completely cleared also presents problems when setting a locking mandrel. Even a slight amount of paraffin on the interior of the wellbore can inwardly compress the lock keys in current locking mandrels. Because the kick keys are forced outward from the locking mandrel by means of springs, paraffin buildup in the wellbore may prevent the lock keys from moving sufficiently outward from the locking mandrel to locate the landing nipple when setting the tool.
Running and setting a locking mandrel will frequently require the use of a “check set” tool that is run into the wellbore to the depth of the locking mandrel and then manipulated to shear a pin to insure the locking mandrel is properly set in the desired landing nipple. The use of a check set tool increases time and expense associated with setting a locking mandrel. The need to run an additional tool also increases the risk that tool or the wireline will be lost in the wellbore tubing requiring difficult and time consuming fishing operations.